Most semiconductor devices require an encapsulating passivation layer to improve their reliability. An insulator such as Si.sub.3 N.sub.4 or SiO.sub.2 is commonly used to passivate compound semiconductor surfaces. The interface between the semiconductor surface and the insulator, however, is poor due to dangling bonds, damage from the insulator deposition and differences in mechanical or physical properties, such as the coefficient of thermal expansion. This poor interface can lead to device problems such as surface leakage current and photogenerated current.
Several attempts have been made to improve this passivation process. One technique is to tie up the dangling bonds at the surface by such techniques as sulfidation or Se terminations. These techniques however have long term stability and process integration problems. Various oxides and nitrides formed by chemical reaction with the semiconductor surface have also been proposed to passivate compound semiconductor surfaces. These processes involve several complicated processing steps and require very precise control of the surface conditions to be successful. Both of these considerations limit their manufacturability.
In a semiconductor devices such as a field effect transistor (FET) properties such as leakage current, breakdown voltage, and saturation current can be affected by its surface properties. Similarly, in an heterostructure bipolar transistor (HBT) the surface properties can limit the gain of the transistor and in a diode the leakage current can be substantially increased. To alleviate these surface related problems a low leakage, stable, low damage process is needed to improve the semiconductor-insulator interface.
It is a purpose of the present invention to provide a new and improved method of passivating semiconductor devices.
It is another purpose of the present invention to provide a new and improved method of passivating semiconductor devices which is relatively simple and inexpensive to perform.
It is still another purpose of the present invention to provide a new and improved method of passivating semiconductor devices which improves various operating characteristics of the semiconductor devices.
It is a further purpose of the present invention to provide new and improved passivated semiconductor devices which are relatively simple and inexpensive to manufacture.
It is still a further purpose of the present invention to provide new and improved passivated semiconductor devices with improved operating characteristics.